Not sure where he said this, or even if he truly said this. His work has been almost completely lost to time, and it’s hard to tell if what’s left is even accurate. That said, Wikipedia credits this quote to a book from Princeton University press. The text for anyone who can’t read it:

“One hundred years is the limit of a long life. Not one in a thousand ever attains it. Suppose there is one such person. Infancy and feeble old age take almost half of his time. Rest during sleep at night and what is wasted during the waking hours in the daytime take almost half of that. Pain and sickness, sorrow and suffering, death (of relatives) and worry and fear take almost half of the rest. In the ten and some years that is left, I reckon, there is not one moment in which we can be happy, at ease without worry. This being the case, what is life for? What pleasure is there? For beauty and abundance, that is all. For music and sex, that is all. But the desire for beauty and abundance cannot always be satisfied, and music and sex cannot always be enjoyed. Besides, we are prohibited by punishment and exhorted by rewards, pushed by fame and checked by law. We busily strive for the empty praise which is only temporary, and seek extra glory that would come after death. Being alone ourselves, we pay great care to what our ears hear and what our eyes see, and are much concerned with what is right or wrong for our bodies and minds. Thus we lose the great happiness of the present and cannot give ourselves free rein for a single moment. What is the difference between that and many chains and double prisons?”